// `panic(logger.ErrCritical)` as done by `logger.CriticalIf`.
//
// It should be always the first / highest HTTP handler.
func setCriticalErrorHandler(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if rec := recover(); rec == logger.ErrCritical { // handle
				stack := debug.Stack()
				logger.Error("critical: \"%s %s\": %v\n%s", r.Method, r.URL, rec, string(stack))